Pick-up trucks have a bed which is used for hauling a wide variety of different things. For many hauling chores (such as carrying sheets of plywood or dry wall, for instance), the owner desires the bed of the pickup truck to present a relatively flat surface. Other chores use a structure, such as a fifth wheel hitch or a gooseneck hitch, which extends above the plane of the pick-up truck bed but is supported or attached through the pick-up truck bed to the underlying frame of the truck. Fifth wheel and gooseneck hitches are more stable than bumper-pull hitches because they are connected to the truck above the rear axle so that the added load of the trailer is applied to rear axle and the pivot of the trailer is at or slightly in front of the rear axle.
Often the bed mounted devices are attached at two or more locations down into the bed of the truck. Some owners desire to be able to switch between such uses, requiring a flat bed at some times and mounting something above the flat bed surface at other times. Accordingly, mounting structures extending above the flat bed surface are preferred to be retractable or easily removable to readily switch to a flat bed configuration.
The most common arrangements are bolted into threaded holes or anchors in or beneath the pick-up bed. Attaching the bolts requires multiple turns of the bolt (so the attachment is secured by multiple thread turns), commonly involving a specified torque applied to the bolts so the bolts don't vibrate loose but without stripping the threads.
More recently, removable/retractable attachment structures have been used which can be changed more quickly than bolted attachments. U.S. Pat. Nos. 6,467,791, 6,502,846, 7,121,573, 7,234,905, 7,793,968 and 7,828,317, all incorporated by reference, disclose examples of non-threaded mounting arrangements in the bed of the pick-up truck which can be quickly removed to provide a flat bed configuration. Mounting arrangements which are stronger, more reliable, less costly and/or easier to employ are needed.